WILL the murder of the Wall Street Journal correspondent Daniel Pearl turn out to be the seminal crime of the 21st century? Those who can so gruesomely destroy an innocent individual may well be capable of destroying millions. For Pearl, as Bernard-Henri Lévy tells us in ''Who Killed Daniel Pearl?,'' was crushed by a granitelike ideological apparatus.

Lévy, in a gripping synthesis of philosophy and reportage, follows the trail of the kidnappers to the highest reaches of Osama bin Laden's Al Qaeda and Pakistan's Inter-Services Intelligence agency, and to the links he claims exist between them. ''On one side a lone man, fragile, representing only himself,'' Lévy writes of Pearl; on the other a ''jihadist syndicate'' vast and formless, comprising both official allies and enemies of the United States. While Saddam Hussein, in Lévy's perceptive words, was a ''tyrant in his autumn, a phantom of 20th-century history . . . in Karachi, tomorrow's barbarous configurations were being concocted.''

Pearl was doubly vulnerable. He was both a Jew and a journalist working alone, away from the media pack, in the chaotic, poor and largely illiterate Muslim city of Karachi, where anti-Semitic conspiracy theories are a prosaic element of daily conversation. His videotaped decapitation at the hands of Islamic terrorists constituted the ritual slaughter of an American Jew who proclaimed his Jewishness at the moment of his death, like a character out of an Isaac Babel story about to be slain by Cossacks. Before the knife fell, Pearl said: ''In Bnai Brak, in Israel, there is a street called Haim Pearl Street, named after my great-grandfather.'' It was that deliberate recovery of such a specific and proud past that kept his tormentors from reducing him to a mere symbol.

Pearl's death also stirred up the ultimate horror of another group: foreign correspondents, who must operate on their own in places where the concept of an independent journalist is so alien that it automatically defines you as a spy or agent. While Lévy's book is the product of a French intellectual -- the author of a study of Jean-Paul Sartre, among other works -- and Mariane Pearl's ''Mighty Heart: The Brave Life and Death of My Husband, Danny Pearl,'' written with Sarah Crichton, is that of a grieving widow, both writers have worked as foreign correspondents, with significant experience in South Asia. It is their professional knowledge that imbues their books with an uncanny profundity about what Pearl experienced the last weeks of his life.

Many a foreign correspondent knows the steady, low-level paranoia -- mixed with boredom and self-doubt -- that one deliberately maintains while squeezed between strangers in the back seat of a vehicle and in slummy apartments in unfamiliar neighborhoods, among militants who are at best uneasy with you, and more likely despise you. Having been in war zones, embedded with United States Army Special Forces and alone with a local fixer inside a Karachi madrasa linked loosely to Al Qaeda, I can say that it is the last of these experiences that is the most unsettling. It is the times you are being served sweet tea and almonds, and everybody acts so polite, when you tend to be the most nervous. Was I smart to trust this fixer? Should I have hired the other guy? What about the driver outside waiting for me?

When things go right, you think yourself a coward for worrying so much. And things do go right until the split second when they go wrong. Then it is too late to affect the outcome: your cowardliness becomes recklessness. Decisions like ''should I get into this car with these people?'' are made on instinct: the unarticulated sum of past encounters. While your instinct improves with such experience, the very knowledge that this is true makes you more inclined to take risks. Whereas being embedded with the military means the loss of freedom in return for extraordinary access and good company, the experience of journalists like Pearl involves radical freedom, which is the epitome of absolute loneliness.

Mariane Pearl describes her late husband as ''a believer in playing it safe.'' She quotes from a prescient memo he wrote to his bosses at The Wall Street Journal about the danger of journalists like himself being kidnapped. He consulted with two security experts about whether he should meet with the Muslim radicals who would later kidnap him at a Karachi restaurant; the experts' advice was inconclusive. Assessing risk in these situations is an art, not a science.

Pearl was lured from the restaurant into a waiting car because of the promise of an interview with Sheikh Mubarak Ali Shah Gilani, an elusive spiritual leader with reputed ties to the pathetic shoe bomber, Richard C. Reid. To arrange that interview, Pearl's fixer had contacted a friend, who in turn contacted a spokesman for the Kashmiri separatist movement, who arranged a meeting between Pearl and a certain ''Bashir'' at a hotel in Rawalpindi. Bashir then put Pearl in touch with one of Sheikh Gilani's disciples. All the while, Bashir's friendly e-mail messages to Pearl suggested the kind of innocuous and protracted runaround encountered frequently by reporters in a part of the world where formal channels are weak and informal networks fill the gap.

Bashir, it turned out, was the British-raised Omar Saeed Sheikh, who had spent six years in an Indian jail for the kidnapping of four foreign tourists who were to be exchanged for an imprisoned Kashmiri separatist. In December 1999, an Indian Airlines plane was hijacked to Taliban-controlled Afghanistan, and in return for the passengers' freedom the Indian government released Omar Sheikh.

''I keep wanting to know how the kidnappers got Danny into the car. He is such a cautious man,'' Mariane Pearl says to a Pakistani counterterrorism expert. ''Did they pull a gun on him? Hit him?'' The man answers patiently: ''Omar Sheikh is an expert. It is Danny who is being kidnapped for the first time. It is Omar Sheikh who has done it 10 times. There is a difference. Omar Sheikh has had a chance to learn from his mistakes. . . . After this, do you think Danny will ever be kidnapped again?''

Though Danny Pearl, as both authors point out, did not consider himself a war correspondent, in a way he was one: in a new kind of war characterized by an unparalleled dispersion of forces. As the modern battlefield expands and empties out, scattered bands of insurgents with increasing access to lethal weaponry hide in broad daylight in civilian areas. Lévy senses that Pearl reached his apotheosis as a reporter while in captivity, when he probably never stopped engaging his jailers, absorbing vital insights about their lives and intentions that could not be had at a safer distance. The 19th-century Prussian philosopher of war Karl von Clausewitz, a product of the Romantic Age, knew that cultural and historical knowledge of the enemy was more important than the elixirs of science and technology. In the cities of South Asia, suffused with the ''stench of the apocalypse,'' as Lévy puts it, Pearl was drinking up the sort of insights Clausewitz valued most.

Lévy's novelistic description of Pearl's death (the translation is by James X. Mitchell) leaves one roiled with emotions. If it was obscene to show the video of the execution, why does one need to read such a meticulously imagined account of it, however savvy it is in the atmospherics: the bleak neighborhood, empty soda cans, curved daggers of the executioners and the fumbling with the camcorder? Lévy's exploration of Pearl's loneliness and indomitable spirit in the moments before he is killed lends gravity to the passage, though.

The same cannot be said about ratings-hungry CBS, whose broadcast of part of the video had no redeeming feature. Mariane Pearl tells Andrew Hayward, the president of CBS News, that her husband's murderers ''appealed to your weakness, and you gave in.''

The news media have altered the strategic landscape. It is questionable whether there would be an incentive for such an execution had there been little likelihood of the video being broadcast -- just as the promise of incessant coverage inspires the perpetuation of violence in both Iraq and Israel. But the news media also included Pearl, who sought knowledge for the sake of analysis rather than mere sensation. As the battlefield of war evolves, journalists like him will be needed more. And the risks will grow rather than diminish.

Robert D. Kaplan is a correspondent for The Atlantic Monthly and the author of many books, including ''Surrender or Starve: Travels in Ethiopia, Sudan, Somalia, and Eritrea.''